Improved Tumor Infiltration and Immunomodulation for Tumor Therapy: A Pathway Based on Tetrahedral Framework Nucleic Acids Coupled Bacterial Nanocells

Nanoparticle/Engineered Bacteria Based Triple-Strategy Delivery System for Enhanced Hepatocellular Carcinoma Cancer Therapy

Background

New treatment modalities for hepatocellular carcinoma (HCC) are desperately critically needed, given the lack of specificity, severe side effects, and drug resistance with single chemotherapy. Engineered bacteria can target and accumulate in tumor tissues, induce an immune response, and act as drug delivery vehicles. However, conventional bacterial therapy has limitations, such as drug loading capacity and difficult cargo release, resulting in inadequate therapeutic outcomes. Synthetic biotechnology can enhance the precision and efficacy of bacteria-based delivery systems. This enables the selective release of therapeutic payloads in vivo.

Methods

In this study, we constructed a non-pathogenic Escherichia coli (E. coli) with a synchronized lysis circuit as both a drug/gene delivery vehicle and an in-situ (hepatitis B surface antigen) Ag (ASEc) producer. Polyethylene glycol (CHO-PEG2000-CHO)-poly(ethyleneimine) (PEI25k)-citraconic anhydride (CA)-doxorubicin (DOX) nanoparticles loaded with plasmid encoded human sulfatase 1 (hsulf-1) enzyme (PNPs) were anchored on the surface of ASEc (ASEc@PNPs). The composites were synthesized and characterized. The in vitro and in vivo anti-tumor effect of ASEc@PNPs was tested in HepG2 cell lines and a mouse subcutaneous tumor model.

Results

The results demonstrated that upon intravenous injection into tumor-bearing mice, ASEc can actively target and colonise tumor sites. The lytic genes to achieve blast and concentrated release of Ag significantly increased cytokine secretion and the intratumoral infiltration of CD4/CD8+T cells, initiated a specific immune response. Simultaneously, the PNPs system releases hsulf-1 and DOX into the tumor cell resulting in rapid tumor regression and metastasis prevention.

Conclusion

The novel drug delivery system significantly suppressed HCC in vivo with reduced side effects, indicating a potential strategy for clinical HCC therapy.

Harnessing tetrahedral framework nucleic acids for enhanced delivery of microRNA-149-3p: A new frontier in oral squamous cell carcinoma therapy

Oral squamous cell carcinoma (OSCC), a type of malignant tumour that primarily occurs in the oral mucosa, has drawn considerable attention owing to its aggressive growth and potentially high metastatic rate. Surgical resection is the primary treatment method for OSCC and is typically combined with radiation therapy and chemotherapy. microRNA-149-3p (miR-149) is a negative regulator of the Pi3k/Akt pathway and can effectively inhibit the proliferation of tumour cells. However, the application of miR-149 is limited owing to its relatively low efficiency of cellular uptake and poor stability when used alone. To overcome these challenges, this study adopted a novel nucleic acid nanostructured material, tetrahedral framework nucleic acids (tFNAs). The use of tFNAs as carriers to assemble the T-miR-149 complex reduced the expression of Pi3k and Akt involved in tumorigenesis and alterations in proteins related to cell apoptosis. The results indicated that the bionic drug delivery system has an effective tumour suppressive effect on OSCC in mice, revealing its potential clinical value in the treatment of OSCC.

Promising dawn in tumor microenvironment therapy: engineering oral bacteria

Despite decades of research, cancer continues to be a major global health concern. The human mouth appears to be a multiplicity of local environments communicating with other organs and causing diseases via microbes. Nowadays, the role of oral microbes in the development and progression of cancer has received increasing scrutiny. At the same time, bioengineering technology and nanotechnology is growing rapidly, in which the physiological activities of natural bacteria are modified to improve the therapeutic efficiency of cancers. These engineered bacteria were transformed to achieve directed genetic reprogramming, selective functional reorganization and precise control. In contrast to endotoxins produced by typical genetically modified bacteria, oral flora exhibits favorable biosafety characteristics. To outline the current cognitions upon oral microbes, engineered microbes and human cancers, related literatures were searched and reviewed based on the PubMed database. We focused on a number of oral microbes and related mechanisms associated with the tumor microenvironment, which involve in cancer occurrence and development. Whether engineering oral bacteria can be a possible application of cancer therapy is worth consideration. A deeper understanding of the relationship between engineered oral bacteria and cancer therapy may enhance our knowledge of tumor pathogenesis thus providing new insights and strategies for cancer prevention and treatment.

Tetrahedral framework nucleic acid loaded with glabridin: A transdermal delivery system applicated to anti-hyperpigmentation

Topical application of tyrosinase inhibitors, such as hydroquinone and arbutin, is the most common clinical treatment for hyperpigmentation. Glabridin (Gla) is a natural isoflavone that inhibits tyrosinase activity, free radical scavenging, and antioxidation. However, its water solubility is poor, and it cannot pass through the human skin barrier alone. Tetrahedral framework nucleic acid (tFNA), a new type of DNA biomaterial, can penetrate cells and tissues and can be used as carriers to deliver small-molecule drugs, polypeptides, and oligonucleotides. This study aimed to develop a compound drug system using tFNA as the carrier to transport Gla and deliver it through the skin to treat pigmentation. Furthermore, we aimed to explore whether tFNA-Gla can effectively alleviate the hyperpigmentation caused by increased melanin production and determine whether tFNA-Gla exerts substantial synergistic effects during treatment. Our results showed that the developed system successfully treated pigmentation by inhibiting regulatory proteins related to melanin production. Furthermore, our findings showed that the system was effective in treating epidermal and superficial dermal diseases. The tFNA-based transdermal drug delivery system can thus develop into novel, effective options for non-invasive drug delivery through the skin barrier.

Bacteria and Bacterial Components as Natural Bio-Nanocarriers for Drug and Gene Delivery Systems in Cancer Therapy

Bacteria and bacterial components possess multifunctional properties, making them attractive natural bio-nanocarriers for cancer diagnosis and targeted treatment. The inherent tropic and motile nature of bacteria allows them to grow and colonize in hypoxic tumor microenvironments more readily than conventional therapeutic agents and other nanomedicines. However, concerns over biosafety, limited antitumor efficiency, and unclear tumor-targeting mechanisms have restricted the clinical translation and application of natural bio-nanocarriers based on bacteria and bacterial components. Fortunately, bacterial therapies combined with engineering strategies and nanotechnology may be able to reverse a number of challenges for bacterial/bacterial component-based cancer biotherapies. Meanwhile, the combined strategies tend to enhance the versatility of bionanoplasmic nanoplatforms to improve biosafety and inhibit tumorigenesis and metastasis. This review summarizes the advantages and challenges of bacteria and bacterial components in cancer therapy, outlines combinatorial strategies for nanocarriers and bacterial/bacterial components, and discusses their clinical applications.

NIR/pH-triggered aptamer-functionalized DNA origami nanovehicle for imaging-guided chemo-phototherapy

Targeted chemo-phototherapy has received widespread attention in cancer treatment for its advantages in reducing the side effects of chemotherapeutics and improving therapeutic effects. However, safe and efficient targeted-delivery of therapeutic agents remains a major obstacle. Herein, we successfully constructed an AS1411-functionalized triangle DNA origami (TOA) to codeliver chemotherapeutic drug (doxorubicin, DOX) and a photosensitizer (indocyanine green, ICG), denoted as TOADI (DOX/ICG-loaded TOA), for targeted synergistic chemo-phototherapy. In vitro studies show that AS1411 as an aptamer of nucleolin efficiently enhances the nanocarrier's endocytosis more than 3 times by tumor cells highly expressing nucleolin. Subsequently, TOADI controllably releases the DOX into the nucleus through the photothermal effect of ICG triggered by near-infrared (NIR) laser irradiation, and the acidic environment of lysosomes/endosomes facilitates the release. The downregulated Bcl-2 and upregulated Bax, Cyt c, and cleaved caspase-3 indicate that the synergistic chemo-phototherapeutic effect of TOADI induces the apoptosis of 4T1 cells, causing ~ 80% cell death. In 4T1 tumor-bearing mice, TOADI exhibits 2.5-fold targeted accumulation in tumor region than TODI without AS1411, and 4-fold higher than free ICG, demonstrating its excellent tumor targeting ability in vivo. With the synergetic treatment of DOX and ICG, TOADI shows a significant therapeutic effect of ~ 90% inhibition of tumor growth with negligible systemic toxicity. In addition, TOADI presents outstanding superiority in fluorescence and photothermal imaging. Taken together, this multifunctional DNA origami-based nanosystem with the advantages of specific tumor targeting and controllable drug release provides a new strategy for enhanced cancer therapy.

Inactive Trojan Bacteria as Safe Drug Delivery Vehicles Crossing the Blood-Brain Barrier

Escherichia coli K1 (EC-K1) can bypass the blood-brain barrier (BBB) and cause meningitis. Excitingly, we find the "dead EC-K1" can safely penetrate the BBB because they retain the intact structure and chemotaxis of the live EC-K1, while losing their pathogenicity. Based on this, we develop a safe "dead EC-K1"-based drug delivery system, in which EC-K1 engulf the maltodextrin (MD)-modified therapeutics through the bacteria-specific MD transporter pathway, followed by the inactivation via UV irradiation. We demonstrate that the dead bacteria could carry therapeutics (e.g., indocyanine green (ICG)) and together bypass the BBB after intravenous injection into the mice, delivering ∼3.0-fold higher doses into the brain than free ICG under the same conditions. What is more, all mice remain healthy even after 14 days of intravenous injection of ∼10⁹ CFU of inactive bacteria. As a proof of concept, we demonstrate the developed strategy enables the therapy of bacterial meningitis and glioblastoma in mice.

Stimuli-Responsive Self-Degradable DNA Hydrogels: Design, Synthesis, and Applications

DNA hydrogels play an increasingly important role in biomedicine and bioanalysis applications. Due to their high programmability, multifunctionality and biocompatibility, they are often used as effective carriers for packing drugs, cells, or other bioactive cargoes in vitro and in vivo. However, the stability of the DNA hydrogels prevents their in-demand rapid release of cargoes to achieve a full therapeutic effect in time. For bioanalysis, the generation of signals sometimes needs the DNA hydrogel to be rapidly degraded when sensing target molecules. To meet these requirements, stimulus-responsive DNA hydrogels are designed. By responding to different stimuli, self-degradable DNA hydrogels can switch from gel to solution for quantitative bioanalysis and precision cargo delivery. This review summarizes the recently developed innovative methods for designing stimuli-responsive self-degradable DNA hydrogels and showed their applications in the bioanalysis and biomedicines fields. Challenges, as well as prospects, are also discussed.